PHOENIX - Arizona voters are entitled to decide if they want to scrap the current partisan system of nominating candidates, the state Supreme Court ruled Friday.

In a brief order, the justices overturned Maricopa County Superior Court Judge Mark Brain, who found the initiative illegally dealt with more than one subject. The justices did not explain their decision, promising details later.

Friday's ruling is a victory for proponents of the change, which would have all candidates, regardless of political affiliation, run against each other for statewide, legislative and county supervisor posts. It also would overrule Tucson's partisan primary for mayor and council.

The top two vote-getters would face off in the November general election.

The "Open Government/Open Elections" initiative still needs to show it has the required 259,213 valid signatures before it actually makes it on to the November ballot.

County election officials are still reviewing a random sample of initiative petition sheets, and some preliminary numbers from the state's largest county suggest the petition drive could fall short.

Maricopa County Elections Director Karen Osborne said she has checked 12,990 of the 13,076 signatures sent to her and found about 67 percent are valid. If that 33 percent failure rate holds up statewide, the petitions could be as many as 19,000 signatures short.

But Tom Milton, the campaign manager, said he believes Maricopa County is much tougher on its checks than other counties, and results from elsewhere will provide enough names to qualify.

If Pima County is any indication, that may be the case: Pima County Elections Director Chris Roads said late Friday the failure rate is running in the 23 percent range.

Supporters of the change contend it will result in general-election candidates whose views are more mainstream than those now nominated only by party voters, as the contenders will have to have broad appeal to survive the primary.

Attorney Mike Liburdi, who represents challengers, scoffed at claims this would make the political system work better.

"These same people who are presenting open government are the same people who presented term limits," he said, which cap the number of years any statewide officer or legislator can serve in the same office. "That didn't fix the problem."

Liburdi said the Citizens Clean Elections Act allowing candidates to get public funding for their campaigns "brought us more extremism and more ideology in the Legislature." And he criticized creation of the Independent Redistricting Commission, saying all that did was move the duty of drawing lines for congressional and legislative districts from the Legislature to a process "orchestrated behind closed doors."

Milton said no one is claiming this measure will transform politics.

"This is not a silver bullet. We believe this is a reform that takes us in the right direction," he said, calling comparisons to the earlier reforms unfair.

Liburdi's initial clients were interests aligned with the Republican Party, whose candidates hold big majorities in the state House and Senate, and all statewide offices with the exception of two of the five seats on the Arizona Corporation Commission. Jaime Molera, a lobbyist and former GOP candidate for statewide office, said the party system works because it gives voters some idea of the general principles of the candidate.

But two Hispanic Democrats also joined in the legal challenge. Rep. Steve Gallardo of Phoenix and Maricopa County Supervisor Mary Rose Wilcox said they are concerned the change being proposed would allow Anglo candidates to "game" the system, making it harder to elect minority candidates, even in districts where they are a plurality or majority.